By Brandon Haley
From the June 2024 Issue
Sustainability and savings are rarely mentioned in the same breath, but smart irrigation practices offer a rare opportunity for both. As water becomes increasingly more expensive across the country, opportunities to conserve a natural resource while reducing costs are becoming more available and attainable.
Whether a site is residential or commercial and managed by onsite, offsite, in-house, or contracted staff, there are opportunities to sell business, save money, and conserve a precious resource. It is common to have irrigation conservation upgrades paid for within 18 months depending on local utility rates. However, this is not a blanket recommendation since there is the possibility that consumption will increase in traditionally underirrigated sites. Careful research of historical utility bills will show the best opportunities for savings.
Smart Irrigation Technologies
Conventional irrigation controllers use static timers to schedule irrigation. While dependable, they are reliant on people to set and adjust their run times and lack the ability to monitor and adjust based on weather or site conditions. Smart irrigation technologies overcome the challenge of a manager’s limited time and capacity for daily monitoring by allowing the system to monitor conditions and self-adjust based on weather, sensor data, and by utilizing rain sensors to halt irrigation during precipitation. With internet connections, the system will also notify end users of the changes.
Smart irrigation automation is driven by internal algorithms that gather information about the site, including plant types, soil, and weather. The controller tailors water applications by increasing water during periods of hot and dry weather and reducing water in response to lower temperatures or excessive cloud cover.
Smart irrigation technologies overcome the challenge of a manager’s limited time and capacity for daily monitoring by allowing the system to monitor conditions and self-adjust based on weather, sensor data, and by utilizing rain sensors to halt irrigation during precipitation.
While no system is perfect, research has shown that the typical smart system in a humid environment can reduce water consumption by up to 43% compared to a professional water manager. Compared to systems that were not managed, savings of over 50% are possible without any additional components being added in the field. In arid conditions where rainfall is limited, these savings will naturally be reduced and there will have to be a higher reliance on increasing the distribution uniformity of the system.
Smart controllers operate fully automatically when equipped with a flow meter and connected to the internet. Properly calibrated flow meters can detect high and low flows within the system and have the controller notify the manager, allowing for remote management. To properly calibrate flow meters, users must ensure there are no leaks in a zone. The lower the deviation allowed, the more water that can be saved.
A simple 1″ mainline break can waste over 20,000 gallons of water a day, with 1″ zone line breaks leaking upwards of 400 gallons per irrigation event. Commercial systems with larger pipes will see much higher amounts of waste from leaks. A broken 2″ pipe can leak over 500 gallons per minute (gpm), moving massive amounts of soil and even collapsing roads if not quickly stopped. Flow meters connected to smart controllers can stop this type of waste within minutes and then send notifications through text or email to the end user, giving them piece of mind that a system is operating properly or an alert when it is not.
Modernizing The Entire System
Technological advances go beyond controllers. Nearly every part of an irrigation system now has a more efficient version, such as pressure reducing irrigation heads, multi-stream spray nozzles, check valves, and improved drip components. Modern irrigation designs that use these more efficient parts can drastically reduce water consumption and present unique, sustainable possibilities for sites. With utility rates for water rising, these water saving components will save water as well as money over their lifespan.
With irrigation components designed to last 10 to 20 years, break-even points as low as three to five years yield financial benefits while saving enormous amounts of money, ensuring landscapes have access to irrigation for years to come.
For municipalities with in-line water pressure above the manufacturer’s recommendation, heads with pressure regulating components offer higher savings. It’s common to have pressure spikes and drops during the night, which increase water consumption. In flow meter-controlled systems with tight tolerances, these spikes can even cause flow to rise enough to trigger high flow warnings and shut down irrigation for the night. Spray heads are the most sensitive to over pressurization with industry data showing flow rates increase by up to one gpm, wasting up to 20 gallons of water per head every cycle.
Multi-stream irrigation nozzles have been proven to increase efficiency of irrigation systems as well. Installed on spray heads, these nozzles use rotating streams of water instead of fixed sprays to irrigate. Their precipitation and flow rates are much lower, typically resulting in longer run times than the spray nozzles they are replacing, which can lead to the perception that they actually using more water than normal nozzles. However, water usage is a function of both time and flow rates, and the reduced flow rate of these nozzles easily makes up for the slight increase in run times. With the increased distribution uniformity and reduced runoff from the low precipitation rate, 20-40% reductions in water consumption are possible with just a simple nozzle change in locations where head spacing allows for the conversion.
Determining ROI & Break-Even Points
To determine the break-even point, divide the total cost of the upgrade by the expected annual savings. This will show the number of years until the cost is paid off. To determine the annual Return on Investment (ROI), divide the annual savings by the total cost. This will equal the percentage annual return of the initial investment. For commercial stakeholders or financially driven customers, ROI will be better understood. For residential stakeholders, the “break-even point” will be a simpler way to explain when irrigation upgrades would be paid off.
Make sure to research the current municipal water rates being charged the local utility and any rebates that may be available to the end user. These rates are typically found online and are presented either in costs per 1,000 gallons or per 100 cubic feet (cu. ft.). One cu. ft. of water is equal to 7.48 gallons and to convert costs per 100 cu. ft. to costs per 1,000 gallons, divide the cost by 0.748.
These rates vary wildly by jurisdiction and can range from $4.00 to over $9.00 per thousand gallons across the country. The current pricing trend has utilities moving from a discounted tier structure to one that favors conservation by raising rates as more water is used. This change has dramatically affected the ROI of irrigation upgrades.
There are a few ways to determine potential break-even points and ROI metrics. For system-wide upgrades such as a smart controller, consider the amount of water used over the course of an entire year for irrigation. Actual metered data is best, but without this information, theoretical averages must be used.
Irrigating an acre of turf for 30 weeks with 1″ of water will use just over 800,000 gallons with 100% efficiency. It is highly likely that the site will be using more than this per acre. With an estimate of 30% savings for a smart controller there is a potential of 240,000 gallons to be saved each year. At a cost of $7.00 per thousand gallons, this presents an opportunity to save approximately $1,680 per acre of irrigated landscape each year.
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For individual irrigation components such as nozzles, consider the amount of water that would be saved by that component individually. For example, using the over-pressurized irrigation head example above, it’s possible save 20 gallons per cycle with pressure regulation. With three scheduled cycles per week over 30 weeks, this represents a potential savings of 1,800 gallons per head. At a cost of $7.00 per thousand gallons, installing pressure regulated heads could save $12.60 annually for each head. Even with installation costs, there is potential for an ROI over 40% and a break-even point under 2.5 years. There are similar examples for rain and soil moisture sensors as recent research in 2022 from the University of Arkansas showed an annual potential savings for rain sensors at $87.00 and soil sensors at $200.00 for Bermudagrass lawns.
Smart Savings
The expected savings of smart irrigation technology contribute to a more sustainable, cost-effective, and customized irrigation system that suits the needs of the site and can use drastically lower amounts of water. Conserving water used for irrigation is rewarding and can be profitable as water rates continue to rise. There are opportunities to both make and save money by upgrading irrigation systems. With irrigation components designed to last 10 to 20 years, break-even points as low as three to five years yield financial benefits while saving enormous amounts of money, ensuring landscapes have access to irrigation for years to come.
Haley, CGM, is VP of Grounds Management for SSC – Services for Education, a University and K-12 facilities services provider. He is a Certified Landscape Irrigation Auditor (CLIA) with the Irrigation Association as well as a Texas-licensed Irrigator. He is also a Certified Grounds Manager through the Professional Grounds Management Society with 25 years of experience in the Green Industry. Haley previously wrote for Turf on “Gas Vs. Electric OPE: Real World Costs.” See that highly informative article here.
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